Titus Livius (Livy), The History of Rome, Book 9
Rev. Canon Roberts, Ed.

36. The Ciminian forest was, in those days, more frightful and impassable than the German forests were recently found to be; not a single trader had, up to that time, ventured through it. Of those present in the council of war, hardly any one but the general himself was bold enough to undertake to enter it; they had not yet forgotten the horrors of Caudium. [2] According to one tradition, it appears that M. Fabius, the consul's brother —others say Caeso, others again L. Claudius, the consul's halfbrother —declared that he would go and reconnoitre, and shortly return with accurate information. [3] He had been brought up in Caere, and was thoroughly conversant with the Etruscan language and literature. There is authority for asserting that at that time Roman boys were, as a rule, instructed in Etruscan literature as they now are in Greek, but I think the probability is that there was something remarkable about the man who displayed such boldness in disguising himself and mingling with the enemy. [4] He is said to have been accompanied by only one servant, and during their journey they only made brief inquiries as to the nature of the country and the names of its leading men, lest they should make some startling blunder in conversing with the natives and so be found out. [5] They went disguised as shepherds, with their rustic weapons, each carrying two bills and two heavy javelins. [6] But neither their familiarity with the language nor the fashion of their dress nor their implements afforded them so much protection as the impossibility of believing that any stranger would enter the Cimiman forest. It is stated that they penetrated as far as Camerinum in Umbria, and on their arrival there the Roman ventured to say who they were. [7] He was introduced into the senate, and, acting in the consul's name, he established a treaty of friendship with them. [8] After having been most kindly and hospitably received, he was requested to inform the Romans that thirty days' provision would be ready for them if they came into that district, and the Camertine soldiery would he prepared to act under their orders.

When the consul received this report, he sent the baggage on in advance at the first watch. [9] The legions were ordered to march behind the baggage, while he himself remained behind with the cavalry. The following day at dawn he rode up with his cavalry to the [10??] enemy's outposts stationed on the edge of the forest, and after he had engaged their attention for a considerable time, he returned to the camp and, in the evening, leaving by the rear gate, he started after the column. By dawn on the following day he was holding the nearest heights of the Ciminian range, and after surveying the rich fields of Etruria he sent out parties to forage. [11] A very large quantity of plunder had already been secured when some cohorts of Etruscan peasantry, hastily got together by the authorities of the neighbourhood, sought to check the foragers; [12] they were, however, so badly organised that, instead of rescuing the prey, they almost fell a prey themselves. [13] After putting them to flight with heavy loss, the Romans ravaged the country far and wide, and returned to their camp loaded with plunder of every kind.

[14] It happened to be during this raid that a deputation, consisting of five members of the senate with two tribunes of the plebs, came to warn Fabius, in the name of the senate, not to traverse the Ciminian forest. They were very glad to find that they had come too late to prevent the expedition, and returned to Rome to report victory.